


Mine & Yours

by EnemiesWithBenefits



Series: self insert undertale [8]
Category: Undertale (Video Game)
Genre: Alternate Universe - Yanderetale, Animalistic, Biting, Blood, F/M, Possessiveness, Pre-Established Relationship, Rutting, Smut, Swelling
Language: English
Status: Completed
Published: 2016-12-17
Updated: 2016-12-17
Packaged: 2018-09-09 03:53:59
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 840
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8874712
Author URL: https://archiveofourown.org/users/EnemiesWithBenefits/pseuds/EnemiesWithBenefits
Summary: You knew Sans could be jealous – but this, this, was something different.





	

**Author's Note:**

> " _m i n e ._ "  
>  865 words, 5 pages.

_You hadn’t meant it –_

 

Sharp phalanges embedded themselves into your hips, trails of blood marking their course from upon your sides.

 

_You didn’t mean –_

 

Boney hips grinding into your own, firm jutting arches that rub against your behind, a deep growl of warning tearing through the air.

 

_This isn’t –_

 

Sharp teeth you’d thought dull dig into your shoulder, tearing through skin and stopping short of truly hurting you beyond repair.

 

He was so _angry._

 

Your hands were thrown above you, coiled in seafoam green magic, racing in sparks, snapping harsh energy against your skin.

 

“ **_m i n e ._** ”

 

You can feel the harsh, demanding press of his cock against your clothed backside, his greedy hands under the already torn fabric. You’re face down on the mattress, pinned by his weight and magic as he teaches you a lesson he’s certain you won’t soon forget.

 

“s-s-sa-” You attempt to choke his name out in a broken sob, only for one of the hands on your hips to reach up and claw down the length of your back, the teeth in your shoulder unlatching enough to work the bloody wound with a rough, sparking tongue. You throw your head back and scream, feeling him laugh breathlessly between snarls.

 

“ **_s h u t i t ._** ”

 

The safeword was on the tip of your tongue, but he distracted you by using the very same hand that'd just bloodied your back to pull your ruined jeans all the way down to expose you. With a rumbling growl that sent the hairs upon your neck standing, you cowered with a soft whine and felt two eager, bloodied phalanges sink into your soaking folds.

 

“ **_w e t ._** ”

 

His face pressed against your own, carved smile worrying suddenly jagged teeth on your earlobe. His bones shuddered with primal strength and magic, a rumbling growl vibrating deep within his sternum and ribs.

 

“ ** _c u n t ._** ”

 

You knew Sans could be jealous – but this, _this,_ was something _different._

 

“ ** _w h o s e ?_** ”

 

Wasting no time the two phalanges pressed inside of you, right to the knuckle. You whined, wet enough to warrant such rough treatment, but still nowhere near prepared.

 

You knew what he wanted.

 

His cock twitched against your backside as he worked on curling his fingers within you, sloppy and rough, all about taking what he wanted. He snarled into your ear, no longer a monster but a beast, ready to fuck you like a bitch in heat.

 

“ ** _W H O S E ?_** ”

 

Another finger inside, the hand still on your hip reach up and disentangling itself from your torn shirt to grip the back of your neck, pushing you ever further into the mattress. His clawed fingers dug into the delicate skin found there, magic sparking against you in angry waves of static.

 

“Y-yours! _Yours yours yours yours yours yo – ”_

 

Without warning, he hilted deep within you, cock hard and firm as he stretched you with a single, merciless thrust.

 

He didn’t stop.

 

You screamed as he set a brutal, punishing pace, relentlessly fucking you like an _animal –_

 

One hand on your neck, the other now on your hip once more, he snapped at you with lumbering snarls and feral, rasping breaths. His hips continued to pump steadily against your own, hard bones bruising the unblemished flesh found there.

 

You could feel him press deep against your cervix with every thrust, your cunt growing tight with fluttering motions of your needy, traitorous body –

 

Eventually, he nearly _roars,_ once again digging serrated teeth into the flesh of your back, and you _break._

 

You come with a wailing, shuddering cry of his name as he continues to pound into you through your orgasm, cock twitching, almost _expanding –_

 

You cry openly now, screaming, begging as he continues to fuck you. His teeth are still embedded in your flesh, the blood on the sheets a vivid carmine of his jealousy.

 

“ **_mine mine mine mine mine mine mine mINE_** – ”

 

It’s isn’t long then until he comes, canting his hips sloppily into your own, with you following close behind. He’s a mess, voice breaking and weight falling on you as the magic keeping you pinned evaporates. He lands on you with a grunt, and you whine in protest – miffed not only by his inconsiderate behavior but with how… _different_ that was.

 

Normally Sans was a considerate, passionate lover – but…

 

“…Sans?” Your voice is weak, a broken whisper directed at the monster lying on top of you almost as still as an actual corpse.

 

“… what?” He sounds calmer, exhausted.

 

“You… okay?” You’re in pain, bleeding and broken beneath him... but... you’re more concerned about _him._

 

“just fine, sweetheart. in fact -” There’s a split second where his magic comes back to life, rewrapping itself around you and pressing you deep into the mattress once more. You’re flipped onto your back, crying out at the feel of open wounds against ruined sheets. Above you, your lover straddles you, a haunting figure with a firestorm of magic bathing him in the darkness. “this’ just _perfect._ ”

**Author's Note:**

> Originally a part of a multi-chaptered work that was never finished, now being seperated into parts.
> 
> Tell me what you think!
> 
> Also, if I forgot any specific tags tell me, please!
> 
>  
> 
> [My tumblr!](http://scripttura.tumblr.com)


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